The present invention generally relates to packaging and more particularly to an apparatus for making unitary packages which hold a plurality of components, each package containing a load wrapped in a web of stretched material which is fastened by a mechanical closure device.
Case packing or boxing is a common way of shipping multiple unit products. The multiple unit products are generally stacked in a corrugated box or are wrapped with kraft paper with the ends of the kraft paper being glued or taped. Another way of shipping such products is by putting a sleeve or covering of heat shrinkable film around the products and shrinking it to form a unitized package. The use of heat shrinkable film is described in U.S. Pat. Nos. 3,793,798; 3,626,654; 3,590,509, and 3,514,920. A discussion of this art is set forth in U.S. Pat. No. 3,867,806.
The present invention provides a simple, reliable and inexpensive method of unitizing multiple unit products into a single wrapped package with an overwrap material which cannot be effectively heat sealed.
When the present apparatus is compared with other apparatus currently used to pack products in corrugated boxes and the cost of the corrugated boxes themselves, the invention shows an enormous cost savings. The invention has comparable costs with kraft wrap but it gives a much tighter and better unitized package than that possible with kraft wrap. In addition to these factors the invention can use stretch film, stretch netting material, or stretch mesh material which provides product visibility not possible with kraft or corrugated wrapping. The netting and mesh incorporates the additional feature of letting the load "breathe." This feature is especially desirable when live produce is packaged and shipped. Furthermore, the present inventive system offers packaging speed, reliability because of the elimination of the package sealing problem and energy savings in that less energy is required to package the product.
A basic problem with shrink and noncling stretch film packaging is that the primary strength and reliability of the package is determined by the consistent quality of the seal. These seals depend on a careful maintenance of the sealing jaw and are never as strong as the film itself. The time taken to make the seals is a limiting factor on the possible speeds of most film packaging systems. Related problems are that some stretchable materials, as for example stretch netting, cannot be heat sealed while narrow film web widths used in spiral wrapping cannot be effectively heat sealed.
In the preferred embodiment the present invention uses a spiral wrapping process to apply the film web to the load.
The use of spiral wrapping machinery to wrap a load is well known in the art. One such apparatus is shown by U.S. Pat. No. 3,863,425 in which film is guided from a roll and wrapped around a cylindrical load in a spiral configuration. A carriage drives the film roll adjacent the surface of the load to deposit an overlapping spiral wrap around the load and returns in the opposite direction to deposit another spiral overwrap around the load. Other spiral wrapping apparatus are described by U.S. Pat. Nos. 3,857,486; 3,788,199; 3,549,017; 3,412,524; 3,191,289; and 2,716,315. The previously indicated patents rely on heat shrink material, adhesives, a heat seal or the tacky nature of the film to hold the outer layer of wrap in a fixed position.
Various other patents have described the use of mechanisms for wrapping loads. In U.S. Pat. No. 3,003,297 a complex cutting and holding mechanism is used to place tape on a box and cut it off with the process being repeated for each box. The unique design and function of the tying, clamping and cutting mechanisms in the present invention does not require a bonding or heating of the film in order for the system to operate.
U.S. Pat. No. 2,088,133 discloses a reverse wrapping wire typing machine. In the reference a gripper mechanism holds a band in position with respect to the load to be wrapped and a rotatable ring drive rotates the band around the load until the band has completed more than one wrap of the load and passes over the body of the gripper mechanism.
A separator slide is used to separate the leading edge of the band from the underlying band and a second gripper mechanism attaches to the separated band. A heat sealing mechanism welds the wrapped layer band to the band underneath it and a cutting mechanism severs the leading edge of the band held by the second gripper mechanism which then becomes the trailing edge of the succeeding wrap. When the band is severed the ring drive mechanism is rotated in a reverse direction for the following load with the various gripping and cutting mechanisms functioning in the same manner.
Additional references of interest which are pertinent to rotatable drives for wrapping packages are disclosed in U.S. Pat. Nos. 3,820,451; 3,331,312; 3,324,789; 3,309,839; 3,207,060; 2,743,562; 2,630,751; 2,330,629; 2,054,603 and 2,124,770.
U.S. Pat. No. 2,124,770 discloses a wrapping apparatus with a clip mechanism for fastening adjacent rope strands. The bundle wrapping machine is automatically operable to wrap a length of rope, or the like, once about a package or bundle, to draw it taut, with its ends in overlapping relation, to apply and cinch one or two metal clips or seals about the overlapped ends to join them permanently together and finally to cut the rope at the outside of the seals thereby to release the bundle. The machine uses paired grippers, one of which is actuated to grip and hold the initial end of the rope during the wrapping operation, while the other is actuated so that it will engage and then grip and hold that portion of the rope that is brought adjacent to the initial end for the clip applying operation. The rope grippers comprise horizontally disposed plungers which extend outwardly to oppose the inward gripping pressure of gripper pressure hooks. As the hooks are pulled inwardly they pull the rope against a sharpened cutting surface of a cutter plate mounted in the end of the top frame. After the clips are applied the rope is cut off outside of the clips to free the bundle with one gripper retaining its hold on the end of the rope leading from the supply, preparatory to a following wrapping operation which will take place in a reverse direction.
Other applications in packaging are shown by U.S. Pat. Nos. 3,514,920 and 3,793,798 in which heat shrink film is wrapped around a pallet supporting a plurality of cartons. A similar full web apparatus using a tensioned cling film is shown by U.S. Pat. No. 3,986,611 while another apparatus using a tacky PVC film is disclosed in U.S. Pat. No. 3,795,086.
The mechanical closure device described in the present specification is a standard "hog ring" type unit such as Model WC6 manufactured by Roto Brand or Model Type I and Type C manufactured by the ATRO Corporation. The slotted pneumatic cylinder used to transport the mechanical closure device is also an off-the-shelf unit available to the public manufactured by the Origa Corporation.
The present invention uses stretchable plastic material in its preferred embodiment since the mechanical stretching of the material utilizes its strength better than heat shrink wrap and can be used on loads where no heat can be applied to the product. The elasticity of the material or film holds the products under more tension than either shrink wrap or kraft wrap particularly with products which settle or relax when packaged.
Various apparatus and processes have been utilized by Lantech, Inc. to use a stretch material in package wrapping. Such apparatus and processes are disclosed in U.S. Pat. Nos. 3,867,806; 4,050,220; 4,077,179; and 4,079,565.